The present invention relates to air abrasion devices and, more particularly, to the control of airborne particulate matter produced by such air abrasion devices in operation by the provision of a gas-liquid aerosol.
Conventional techniques for repairing or otherwise treating teeth in dental procedures such as the removal of caries or in the manufacture/repair of dental prosthetics (eg. crowns, dentures) typically involve the use of rotary drills. These drills perform at preset speeds; typically xe2x80x9chigh or xe2x80x9clowxe2x80x9d. As a result, these instruments lack fine control and are imprecise. Furthermore, the drilled surfaces are relatively smooth and accordingly are generally not ideal surfaces for adherence of the metals, porcelains, acrylics and/or composites routinely used in dental practice.
As an alternative to rotary drilling, the use of air abrasion, wherein an abrasive material is conveyed by a rapid air current to impinge forcefully against, and thereby remove through abrasion, unwanted tooth material, is attractive. In the field of micro-dentistry, air abrasion has current but limited use extending to both intra (ie. removal of caries) and extraoral (ie. dental prosthetics) applications. A major advantage of air abrasion in micro-dentistry (AAMD) over conventional rotary drills is that it is more precise and affords the user much more control in the aforementioned intra and extraoral applications. Additionally, AAMD typically results in uneven surface areas which are more amenable to secure receipt of adhesives. Further, anaesthetic is often not required.
Notwithstanding the apparent advantages of AAMD over conventional rotary drilling, the use of the former has been limited by technical and health-related difficulties. Conventional AAMD devices are not capable of controlling airborne emissions of the abrasive material, nor of the abraded material, either inside the mouth of the patient or to the dental operating theatre. Common abrasive materials include sodium hydroxide and aluminum oxide powder of 27.5 to 50.0 microns in particle size which travels easily in ambient air as dust to foul machinery and other instruments within and generally soil the operating theatre. Further, in the case of powdered aluminum oxide, its aluminum content makes it a toxicological risk for Alzheimer""s Disease. Meanwhile, the abraded materials may include as a component abraded dental amalgams which can contain toxic constituents such as mercury, such that use of AAMD for amalgam removal is prohibited in certain jurisdictions. This contamination of dental operating theatres persists in current applications despite the use of high efficiency particulate air (HEPA) vacuum systems. Furthermore, extensive use of intraoral latex rubber dams is also necessary to aid in the prevention of inhalation of the respirable aluminum powder by patients, which is also problematic in light of latex-associated asthmatic and respiratory-type reactions. Moreover, as neither prevention technique is particularly efficient or effective, the continuance of exposure to the abrasive material and abraded materials and the attendant potential for health complication(s) remains of concern to both patients and dental professionals.
In addition, although existing AAMD devices are capable of tooth polishing operations, the technology is currently not widely exploited in this application because such operations are typically quite lengthy in duration, and may result in significant operatory contamination as previously described.
It is known in the prior art to surround the abrasive stream with a curtain of water, so as to minimize contamination. An example of such a prior art device is disclosed in U.S. Pat. No. 3,972,123 (Black), issued Aug. 3, 1976. By utilization of sufficient amounts of water, so as to form a continuous curtain surrounding and impinging upon the soluble abrasive stream, airborne contaminants can be controlled, but this may have deleterious affects upon the ability of the technician to view the target area. Further, the volume of water utilized may require significant evacuation efforts with conventional liquid suction systems, impeding the ability of the technician to complete the operation at hand, and adding to the overall discomfort to the patient The device is also intended for the cleaning of teeth, only, and not for use in restoration procedures.
In light of this prior art, the development of an abrasion device that provides improved dust suppression would be considered revolutionary within the field of micro-dentistry, in that it would create better visibility for the dentist, create healthier conditions, make practical extra and intra-oral usage and eliminate the need for costly high efficiency particulate air (HEPA) filter vacuum units.
Similar benefits and drawbacks as previously discussed apply in relation to the use of known air abrasion devices in medical surgery, for removal of unwanted bone material. (Of course, the concern as to airborne abraded amalgam does not apply in the context of medical surgery, as such amalgams are typically not present.) As well, if an air abrasion device incorporating effective dust suppression technology were produced, same would no doubt find utility in other fields, such as, for example, in tools for arts and crafts, or for use in fine manufacturing operations, for example, in the computer industry.
It is therefore an object of the present invention to provide a novel abrasion device with improved dust suppression.
In one aspect of the present invention, there is provided an abrasion device comprising a first delivery means for delivering an abrasive material to a target region; a supply means for supplying a fluid, said fluid comprising a gas-liquid aerosol; and a second delivery means for delivering said fluid near said target region under conditions sufficient to suppress airborne emissions of said abrasive material from said target region.
Preferably, the first delivery means includes a head and a nozzle mounted on the head with a first conduit therein to receive the abrasive material. The second delivery means includes a plurality of second conduits near the first conduit to receive the fluid. The second conduits are arranged so that the fluid leaving them generates, for example, a curtain-like stream toward the target region. In other words, the individual fluid streams leaving the second conduits converge to a hollow substantially continuous stream to define an inner region. Conveniently, the first conduit may be arranged to deliver the abrasive material to the inner region. The pressure and content of the fluid can thus retard or, in some cases prevent, airborne abrasive material from breaking through the curtain, either causing it to be entrained in the fluid or to be repelled back into the inner region.
The fluid may be provided in a variety of forms including an aerosol of water and a gas such as air, or other suitable gases such as nontoxic or inert gases, for example, nitrogen or carbon dioxide. The fluid itself may be dispensed, if desired, at pressures ranging from 5 to 75 psi, for example. It is also contemplated that the fluid may comprise disinfectants, so as to reduce the likelihood of operatory infection and to increase communicable disease control.
In another aspect of the present invention, there is provided an abrasion device comprising a first delivery means to deliver abrasive material to a target region and a second delivery means to deliver a supply of a fluid, said fluid comprising a gas-liquid aerosol, near said target region under suitable conditions for retarding the passage of airborne abrasive material therethrough.
Preferably, the fluid forms a curtain around the target region. More preferably, the curtain completely encircles the target region.
In still another aspect of the present invention, there is provided an abrasion device operable to deliver an abrasive material stream to a target region and a fluid stream, said fluid comprising a gas-liquid aerosol, near said target region under conditions sufficient to suppress airborne abrasive material emissions from said target region.
In still another aspect of the present invention, there is provided a method of abrading a target, comprising the steps of delivering a first supply of abrasive material to a target region and delivering a second supply of a gas-liquid aerosol near said target region, wherein said gas-liquid aerosol has sufficient volume and pressure to form a barrier to airborne abrasive material.
Thus, the invention provides an abrasion device that utilizes abrasive dust as the abrasive material, and which provides effective dust suppression by the use of a stream of a gas-liquid aerosol, such as, for example, an air-water aerosol. In this example, the device emits a stream of the abrasive material as well as the air-water aerosol, the latter under conditions sufficient to minimize the amount of dust leaving the target region and thus control widespread contamination by the airborne abrasive material.
The abrasion device may be hand controlled, by way of xe2x80x9cpush buttonxe2x80x9d or xe2x80x9ctouch sensoryxe2x80x9d controls. Furthermore, the controls may be such that the gas-liquid aerosol and the abrasive stream are continuously variable, are regulated in a stepwise manner (ie. high-medium-low), or are controlled in a simple on-off manner. The device may also be used with a foot pedal or other such control mechanisms. The invention may also control the composition of the abrasive material stream and the gas-liquid aerosol, such as pressure, flow rate, temperature and the like. The device can also be made adaptable to operatory compressors, and water and electrical supply outlets as allowed by available technology.